A 35-year-old arrested on Monday in relation to the attempted murder of PSNI officers in Derry has been released from custody unconditionally.
Gunmen targeted police in the Glen Road area of the city on Wednesday night.
Officers came under fire as they examined a car which had been abandoned.
The attack was claimed by the Real IRA.
In a statement to a local newspaper, the dissident group warned more attacks would follow.
The 35-year-old man was arrested in the Creggan Estate area of the city on Monday morning and has now been released.
Meanwhile, a 31-year-old man detained in Derry on Saturday in relation to the attack was also released unconditionally the following day.